The invention relates to improvements in methods of making absorbent materials, for example, granules, pellets or other relatively small particles which can be used as litter, as oil binding materials or for related and analogous purposes. Still more particularly, the invention relates to improvements in methods of making absorbent particles which contain paper. The invention also relates to granules, pellets and like particles which are produced in accordance with the method.
Economical reuse of paper (including discarded newspapers, magazines, brochures, pamphlets and analogous publications as well as cardboard boxes and relatively clean (e.g., unprinted) discarded industrial paper) is gaining in importance at a rapid rate. Such paper is segregated from household waste and/or from industrial waste and/or is offered by paper recycling plants. Waste paper or recycled paper is one of numerous materials which are used to absorb water, urine, oil and/or other liquid substances. In addition to organic materials (such as shavings of wood, textiles and paper), it is also known to employ inorganic (such as mineral) substances including, for example, alumina, limestone, montmorillonite and many others. As of late, the utilization of inorganic raw materials for the making of litter or oil binding materials is considered to constitute an unacceptable waste of valuable natural resources. Moreover, the disposal of inorganic absorbent substances subsequent to their use as litter or oil binding material is a costly and time-consuming procedure. As a rule, such disposal involves piling up saturated inorganic materials at waste material gathering sites or combustion which, in turn, involves the development of excessive quantities of slag.
Waste paper is a presently preferred material which is to be converted into litter for cats, rabbits, hamsters and other relatively small animals which are kept in houses or apartments. As a rule, waste paper is comminuted by resorting to an impacting tool or by grinding in a mill. The thus obtained fragmentized waste paper is mixed with water and is converted into granules, pellets and/or similar relatively small particles. A drawback of such particulate material (when used as litter) is that the particles decompose on contact with urine and are converted into pulp or mush which complicates the disposal of such materials. Proposals to prevent decomposition of water-containing particles of litter include the admixture of certain additives.
Certain heretofore known proposals to make absorbent particles for use as litter or for other purposes are described in U.S. Pat. Nos. 4,263,873, 4,378,756, 4,409,925, 4,532,890, 4,560,527 and 4,607,594, in Canadian Pat. No. 1,172,025, in Dutch patent application No. 8304094, in French Pat. No. 2,618,641 and in published European patent application No. 0 121 055.